The great versatility of programmable logic controllers permits the programmable logic controller to monitor and control virtually any type of operating system. In the past, programmable logic controllers were frequently hard-wired to various sensors and devices within the system for monitoring and controlling their operation. Hard-wired installations limit the flexibility and adaptability of the programmable logic controller by preventing connection of the programmable logic controller to another component in the operating system or to another operating system. Multi-wire electrical connectors are increasingly being used for connecting the programmable logic controller to the operating system or a component therein to provide this flexibility. Because the electrical leads carry power, sensor and control signals and because the operating environments of such systems are frequently hostile and subject to shock, vibration, and other stresses, electrical connectors used in such applications must be rugged, easily installed and removed, and must accommodate a plurality of discrete conductors.
These types of connectors frequently include a threaded coupling nut attached to a molded connector body with conductive pins or inner contacts which is adapted for coupling to a mating connector assembly. The threaded coupling nut is subject to loosening due to shock and vibration such as encountered in many common manufacturing environments. Once the threaded coupling nut becomes unseated, removal of the plug-like leads from the socket portion of the connector is easily accomplished, resulting in a breaking of the electrical connection. In addition, it is difficult to determine the extent to which the coupling nut is secured. If it is turned too much, deformation or damage may result. If the nut is not fastened enough, the tendency to become loose is greater.
The present invention addresses the aforementioned limitations of the prior art by providing a high strength, locking, vibration resistant electrical coupling which also affords a user a tactile indication of tightening and locking of the connector portions.